some other animals use sound and the ability to hear. birds , as we know , make a wide variety of sounds-from cheeps and chirps to hoots and caws-all understandable by their own kind. whales , too , seem to communicate by sound. according to some scientists , they sing 'songs' which other whales can hear many kilometres away! while the scientists are uncertain what the songs mean , they have no doubt the whales use them to talk to each other.